1. Field of the Invention
The present invention generally relates to an image forming system and, more particularly, to an image forming system in which a plurality of image forming apparatuses such as digital copy machines are connected by a transmission path to transmit image data therebetween.
2. Description of the Related Art
Conventionally, an image forming system which increases a processing speed by connecting a plurality of image forming apparatuses such as copy machines is used. In such a conventional image forming system, image data is transmitted between the copy machines by using either a method in which uncompressed raw image data is transferred together with a main-scanning gate signal and a sub-scanning gate signal or a method in which image data to be transmitted is subjected to a variable-length encoding similar to a facsimile apparatus and thereafter the encoded image data is transmitted by a packet communication.
For example, Japanese Laid-Open Patent Application No. 2-60277 discloses a technique in which image data obtained by scanning is temporarily stored in a memory without being processed, and thereafter the image data is distributed to peripheral devices via an interface such as an SCSI.
In the above-mentioned image forming system, a malfunction may be found at a time when a copying operation is performed in a state in which one copy machine is connected to another copy machine. In such a case, a position in which the malfunction occurs cannot be specified.
In order to eliminate such a problem, a malfunction diagnosis may be performed when a power of each image forming apparatus such as a copy machine in the image forming system is turned on. However, in such a method, a transmission line between the image forming apparatuses is not checked. Accordingly, a malfunction of the transmission line may be found at a time when image data is transmitted through the transmission line for performing, for example, a copying operation in a connecting mode in which image data is transferred from one copy machine to another copy machine.
The image forming system mentioned above is generally designed for office use. Accordingly, it is always possible that a malfunction occurs in the transmission line such as a transmission cable connecting the image forming apparatuses.